SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '948b1f6019ca2823d24dd519fffa40af6edacbcb3ab30feaf14487abb3c4d3c6' 
  AND token = '6XveK/OF9Brv0kgb7YfgwQTHmoTA0moU1rvxAToUheE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}